The present invention relates to a method for determining a characteristic number for characterizing a quality of a shade setting of a paint. The present invention further relates to a computer program for implementing the method of the invention.
In the mixing of a paint, i.e., in the case of a shade setting, different shades are mixed and then compared with a color reference or a shade original. For this purpose, traditionally, the mixed paint is measured spectrophotometrically and resultant measurement values, i.e., for example, colorimetric coordinates, are compared with corresponding measurement values for the color reference. Particularly in the case of effect paints comprising a number of effect pigments, a meaningful comparison between a particular effect paint and a particular color reference is possible only using measurement values determined under different measurement geometries. This means that in order to compare a paint with a color reference, it is necessary to determine a multiplicity of measurement values for a multiplicity of measurement geometries.
There are methods known in the prior art which provide for limited comparison of a particular paint with a particular shade original, i.e., color reference, without taking account of any effect pigments present, for only three measurement geometries.
Publication WO 2013/049796 A1 relates to a method for comparing a paint with a reference, the reference used being color characteristics of a color formula.
Publication DE 102 08 696 A1 discloses a method wherein colors approximated to a metallic color are calculated by means of color classification codes.
The US-American publication US 2011/013176 A1 discloses a method for determining properties of a surface.
It is against this background that a method is presented for determining a characteristic number for characterizing a quality of a shade setting of a paint in relation to a color reference, wherein colorimetric coordinates of the paint and of the color reference are determined with a spectrophotometer for a number of measurement geometries and wherein respective color differences are calculated and standardized from the colorimetric coordinates of the paint and of the color reference for each measurement geometry of the number of measurement geometries, and where a group of characteristic values calculated from the respective standardized color differences is assigned a scale value for determining the characteristic number by means of an assignment rule to be provided in advance.